This invention relates generally to tubing sets used in the administration of liquids to a patient that are commonly referred to as intravascular (“IV”) sets and more particularly concerns bubble free, self-priming IV sets. An IV set according to the invention is used broadly herein to describe tubing sets used in the arterial, intravenous, intravascular, peritoneal, and non-vascular administration of fluid. Of course, one of skill in the art may use IV set to administer fluids to other locations than those listed within a patient's body.
One common method of administering fluids into a patient's blood flow is through an IV set. An IV set is an apparatus that generally includes a connector for connection to a fluid reservoir, a drip chamber used to determine the flow rate of fluid from the fluid reservoir, tubing for providing a connection between the fluid reservoir and the patient, and a connector for attachment to a catheter that may be positioned intravenously in a patient. An IV set may also include a Y-connector that allows for the piggybacking of IV sets and for the administration of medicine from a syringe into the tubing of the IV set.
It is a generally good practice to remove air from IV sets which access a patient's blood flow. While this concern is critical when accessing arterial blood, it is also a concern when accessing the venous side. Specifically, if air bubbles are allowed to enter a patient's blood stream while receiving the intravenous administration of liquids, the air bubbles can form an air embolism and cause serious injury to a patient.
Normally, in a majority of adults, the right atrium and the left atrium are completely separated from each other so that the blood and air bubbles are moved from the right atrium, to the right ventricle, and then to the lungs where the air bubbles may be safely vented. The bubble free blood is then returned to the left atrium, where the blood is moved to the left ventricle and then sent throughout the body.
However, in infants and in a small portion of the adult population, the right atrium and left atrium are not completely separated. Consequently, air bubbles can move directly from the right atrium into the left atrium and then be dispersed throughout the body. As a result, these air bubbles may cause strokes, tissue damage, and/or death. Therefore, it is important to prevent air bubbles from entering a patient's blood stream.
In spite of the importance of removing air bubbles while priming an IV set for use in the intravenous administration of liquids, the complete removal of air bubbles can be a time consuming process. The process may also lead to contamination of the IV set by inadvertently touching a sterile end of the IV set. Typically, when an IV set is primed, a clamp is closed to prevent liquid from moving from a drip chamber through the tubing. The IV set is then attached to an IV bag or bottle. Once attached, the drip chamber, which is typically made of a clear flexible plastic, may be squeezed to draw the liquid out of the IV bag or bottle and into the drip chamber. The drip chamber is allowed to fill about ⅓ to ½ full when the clamp is opened to allow liquid to flow through the tube to an end of the IV set.
This initial process, however, typically traps air in tubing which must be removed. For example, the flow of the liquid through the tubing of the IV set may be turbulent and can entrap air within the tube as the boundary layer between the liquid and the tubing is sheared. The flow rate out of the drip chamber may be higher than the flow rate of liquid entering the drip chamber. This can cause a bubble ladder to form as air is sucked from the drip chamber into the tubing.
Additionally, air bubbles may be generated as drops of liquid strike the surface of the pool of liquid within the drip chamber. These air bubbles can be pulled into the tubing of the IV set from the drip chamber. This problem may be aggravated in pediatric applications where the drip orifice may be smaller which may result in increased turbulence.
To remove air bubbles from the IV set, liquid from the IV bag or bottle is allowed to flow through the tubing while an attendant taps the tubing to encourage the air bubbles out the end of the IV set. As the liquid is allowed to flow out of the IV set to clear air bubbles from the tubing, the liquid is generally allowed to flow into a waste basket or other receptacle. During this procedure the end of the tubing may contact the waste basket or be touched by the attendant and thus, become contaminated. An additional shortcoming of this debubbling process is that it requires attention and time that could have been used to perform other tasks that may be valuable to the patient.
Another debubbling method is to directly remove air bubbles from the IV set. More specifically, if the IV set includes a Y-connector, air bubbles may be removed at the Y-connector by a syringe.
In some cases, a small pore filter may be used in the drip chamber to prevent air from entering the IV tubing from the drip chamber. However, the bubbles formed from the dripping action may become trapped on the filter, thus, reducing the flow of liquid through the filter to the IV tubing. However, the filter is normally positioned so that air may be trapped between the bottom of the filter and the bottom of the drip chamber.
Accordingly, a need exists for an IV set that is self-priming and bubble free, and which does not require constant attention and supervision. Additionally, a need exists for an IV set that prevents bubbles from entering the tubing during use, while providing flow rates that satisfy the needs of the patient.